Biomass and other very light materials which have bulk densitites as low as 1 to 5 lbs./cu. ft. are impossible to briquette in conventional roll briquetters. Materials included are silica fume, fiber glass furnace dust, shredded paper, and shredded currency. These materials have a very low bulk density and the individual particle size is for some of the material is approximately one micron. In order to densify these materials they must first be deaerated so that briquettes can be formed which contain very little compressed air.